Curve scriber



Sept, 1, 1953 v. DEBS CURVE SCRIBER Filed June 21, 1952' INVENTOR V/CTORDEBS BY ATTORNEY Patented Sept. 1, 1953 UNITED STATES PATENT OFFICECURVE SCRIBER Victor Debs, Ridgewood, N. Y.

Application June 21, 1952, Serial No. 294,838

5 Claims. 1

This invention relates to a curve scriber, and more particularly to aninstrument which will scribe a Variety of mathematical or geometricalcurves. The invention is especially useful in scribing ellipses, ovoidforms and spirals, to which uses, however, it is not restricted.

A variety of curve-scribing instruments have heretofore been designedand constructed, and some of such instruments have actually been putupon the market. However, such instruments have generally beencomplicated and expensive. They have also been delicate, difiicult toadjust and to keep in adjustment; and they have been subject toinaccuracies due to entrance of the human equation into their operation.

I have now constructed a curve scriber which is simple, inexpensive andrugged. Adjustment of the instrument with respect to character and sizeof the curve to be scribed is easily and accurately made, and isretained with certainty. Furthermore, a scriber according to theinvention is so constructed that the human equation enters to a minimumextent into its operation.

According to the invention, means is provided whereby the markingelement of the scriber is maintained at all times in perpendicularposition with respect to the surface upon which the curve is to bescribed. Furthermore, means is provided for insuring a constant and evenpressure of the marking element upon this surface. Finally, theinvention provides means which compensates any unevenness in tensionwhich a user may apply to the scriber during its operation, therebyminimizing the effect of the human equation in using the instrument.

The invention contemplates other advantageous and novel features, aswill appear from the present specification.

One form of the invention is shown by way of illustration in theaccompanying drawings, in which Fig. 1 is an elevation, partly insection, illustrating a curve scriber constructed and arranged accordingto the invention, the curve scriber being set up to scribe an ellipsewhich is shown in perspective;

Fig. 2 is a longitudinal horizontal section of the curve scriber shownin Fig. l, the section being taken on the line II-II of Fig. 1;

Fig. 3 is a vertical section taken on the line III-III of Fig. 1, viewedin the direction of the arrows, most of the apparatus appearing inelevation;

Fig. 4 is a perspective view of one of the specially-formed pins usedwith the curve scriber;

illustrated in Figs. 1, 2 and 3, there is shown a curve scriber Hi,comprising a standard H, a bracket i2 hinged to the standard, and amarking element holder I3 slidably carried by the V bracket ['2 formovement toward and away from the standard H. A marking element 14 isreciprocably mounted in the marking element holder l3 for free verticalmovement therein. Thus the standard I l and the marking element [4 areswiveled with respect to each other by means of the bracket l2 and themarking element holder [3, and the slidable mounting of the holder inthe bracket permits the standard and the marking element to be broughtcloser together or to be farther separated.

The standard ll comprises a circular foot l5 having a plane annularlower surface [6 adapted to rest slidably upon a plane surface, as theupper surface of a piece of paper upon which the curve scriber I0 isused. A central concave portion l! at the bottom of the foot l5 insuresagainst wobbling of the foot when it rests upon the plane surface. Ashaft 18 is fixed centrally in the foot l5 and extends perpendicularlytherefrom when the foot rests upon a horizontal surface; and a sleeve [9is closely fitted upon the shaft for rotation thereon. The bracket I2 isfixed to the sleeve l9, which hinges the former to the standard. Finallya handle 20 is fixed to the upper end of the shaft I 8 beyond the sleeveIS in order that the standard may be moved about on the horizontalsurface.

The bracket l2 comprises two vertical parallel plates 2| and 22integrally connected together by a web 23 across their upper edges. Theparallel plates 2| and 22 are fixed to the sleeve I9 as by welds 24 and25 respectively (see Fig. 2) and extend horizontally from the sleeve.Thus the bracket I2 is free to move with the sleeve [9 pivotally aboutthe shaft I8. The plates 2| and 22 have parallel slots 26 and 21 thereinextending longitudinally thereof at right angles to the axis of thesleeve 19 from points adjacent the welds 24 and 25 to the ends of theplates.

The marking element holder l3 comprises a tubular member 28 which isfixed to the end of a forked member 29 as by welds 35 and 3!. (See Fig.2.) The forked member 29 has a pair of legs and 33 which are separatedby a sufficient distance to enable them to fit closely, but slidablybetween the plates 2! and 22 of the bracket 52. Furthermore, the legs 32and 33 have slots 34 and 35 respectively therein which register with theslots 26 and 21 in the plates 2! and 22 respectively. However, the slots34 and 35 are made wider than the slots 25 and 21 for a purpose whichwill later appear.

A pin 35 extends through the unslotted ends of the legs 32 and 33 remotefrom the holder l3, and fits slideably into the slots 25 and 21 in theplates 2| and 22 to guide the forked member 29 as it slides back andforth in the bracket l2. A second pin 31 of larger diameter than the pin36 extends through suitably enlarged portions of the slots 25 and 21 inthe plates 2| and 2-2 and also through the slots 34 and 35 in the forkedmember 29 for a purpose which will later appear. Split rings 38 and 39snap in well known manner into circumferential grooves (not shown) inthe second pin 31 immediately beyond the outer surfaces of therespective plates 2! and 22 to fix the second pin 31 in position duringoperation of the curve scriber. Thus the pins 36 and 31 constrain theforked member for motion at right angles to the shaft I8.

A helical compression spring 45 is disposed between the end of slots 34and 35 of forked member 29 and the pin 31 in the space between the legs32 and 33 of the forked member 29, the diameter of the spring being suchas to cause a part thereof to extend partly into each of the slots 34and 35, whereby the spring is steadied.

From the foregoing it will be evident that sliding movement of theforked member 29 in the bracket 12 away from the sleeve 19 will beresisted by the resiliency of the compression spring 40. Moreover, byremoving the split rings 38 and 39 from second pin 31, that pin may bewithdrawn, and the helical compression Spring 40 released. The markingelement holder ['3 may thus be separated from the bracket l2.

The marking element M has a cylindrical stem 4| thereon which fitsclosely but slideably into the tubular member 28. A transverse pin 42fixed in the stem 4| of the marking element extends outwardly through alongitudinal slot 43 in the tubular member 28 to prevent turning of themarking element in the tubular member; and a weak sprin 44 is compressedwithin the tubular member between its closed top and the top of the stem4! to urge the marking element gently out of the tubular member, that isto say downwardly. As here shown, the top of the tubular membercomprises a threaded plug 45, whereby the force exerted by the weakspring upon the top of the cylindrical stem 4| may be adjusted.Accordingly, when the lower surface IQ of the circular foot rests uponthe paper or other surface upon which a curve is to be scribed, themarking element M will make suitable contact with the paper or surface,through the force of gravity and the gentle urging of the weak spring44, Thus means is provided for insuring a constant and even pressure ofthe marking element upon the surface upon which the curve is beingscribed.

The slot 43 has a transverse hooked extension 455 at its upper endthereby making it possible to move the marking element inwardly of thetubular member 28 against the resiliency of the weak spring 44 and, byturning the marking eled ment, to hold it upwardly in the holder 13 outof contact with the surface upon which it acts. In such inoperativeposition, there is no objection to having the marking element turned inthe tubular member 28.

The curve scriber is operated in conjunction with a loop of thread in amanner later to be described. For this purpose a thread reel 41 ismounted upon a bracket 48 fixed in known or convenient manner to thetubular member 28 at the opposite side thereof from that hearing thewelds 3E! and 3i. The bracket 48 is a forked member the legs of whichextend away from the tubular member, each leg having a round opening 49therein for reception of a split shaft 50 of the thread reel 41. Aknurled head 5! at one end of the split shaft provides means for turningthe thread reel in the bracket 48. A looped thread 52 is wound about thesplit shaft 56 of the thread reel between the forks of the bracket 48and extends thence through an opening 53 in a downwardly extending guidemember 54 forming part of the holder [3. Passing along the guide member54 the thread 52 passes through a terminal slot 55 at the lower end ofthe guide member 54, whence the looped thread extends horizontally awayfrom the marking element l4 and the standard H to engage a plurality ofdouble conical location elements 56 (see Fig. 4). The double conicallocation elements 55 are each formed with a central waist 51 andopposite terminal cone bases 58; and a pin 59 is positioned centrally ofeach terminal cone base 58 for insertion into the surface upon which thecurve is to be scribed to position the location element thereon. Thedouble conical elements 56 are so formed that, when positioned upon thesurface upon which a curve is to be scribed, their central waists 51will be at the elevation above the surface at which the standard Hsupports the terminal slot 55 of the guide member 54.

In the embodiment illustrated in Fig. l the curve scriber is shown asset up for scribing an ellipse, the marking element 14 being illustratedas a draftsmans pen. The curve scriber is used todescribe an ellipse inthe following manner: Two of the double conical location elements 56 arepositioned at the foci of the ellipse to be scribed. To this end a pin59 of each element is thrust through the paper upon which the ellipse isto be drawn and into the drafting board beneath it until a terminal conebase 58 of each element rests evenly upon the upper surface of thepaper. Thereupon the neck of the reversely conical location pins is atthe elevation of the terminal slot 55 of the guide member 54 when thecircular foot l5 of the standard H rests upon the same surface. Thedoubled or looped thread is next partially unwound from the thread reel41, drawn a sufficient distance through the opening 53 and the terminalslot 55 in the guide member 54, and looped about the central waists 51and 51 of the two double conical location elements 56 and '56. Themarking element I4, which has been partly withdrawn into the tubularmember 23, with its transverse pin 42 in the hooked extension '46 of thelongitudinal slot 43, is now turned and allowed to move partly out ofthe tubular member. In effecting this, the transverse pin 42 slides inthe longitudinal slot 4-3, and remaining in the longitudinal slot,prevents the marking element from turning in the tubular member. Thescribing point of the marking element I 4, as the marking end of the penillustrated in Fig. 1, is now placed at one end of the major axis of theellipse to be scribed. Thereupon the knurled head is turned to wind anyslack in the thread 52 upon the split shaft 50 until the thread ispulled gently taut about the central waists 51, 51 of the double conicalelements 56, 56 and through the terminal slot 55 of the guide member 54.In this condition the looped thread extends horizontally above thepaper.

Grasping the handle 20, the standard H is drawn slightly away from themarking element holder l3, compressing the helical spring 40 to alimited extent. This is possible because the marking element holder isrestrained by the tension of the thread 52 which is looped about thedouble conical elements 56. Maintaining substantially even tension inmanipulating the handle 20, the standard II is moved completely aroundthe two double conical location elements 56, 56, causing the markingelement I 4 to scribe the ellipse. The size and character of the ellipseis, of course, governed by the distance between the double conicalelements and by the length of the looped thread between the farthestdouble conical element and the guide member 54.

The circular foot I5 and the shaft l8 extending vertically therefromprovide means whereby the marking element I4 is maintained at all timesin perpendicular position with respect to the surface upon which theellipse is scribed. Inaccuracies in scribing the ellipse which mightresult from holding the marking element at an angle to the vertical arethus avoided. Furthermore, the force of gravity upon the marking elementM, which is freely slidable in the vertically-positioned tubular member28, plus the action of the weak spring 44 upon the marking elementinsures a constant and equal pressure of the marking element upon thesurface on which the curve is being scribed. Finally the relationship ofthe marking element holder and the standard, together with the action ofthe compression spring 40, provides means which compensates anyunevenness in tension which a user may apply to the scriber during itsoperation. Thus, little variation results in the tension applied to thelooped thread 52, and the looped thread is not stretched. The efiect ofthe human equation in using the instrument is accordingly minimized.

Instead of drawing the curve with a draftsmans pen as illustrated inFig. 1 it may be desired to draw the curve in pencil. A marking elementfor this purpose is illustrated in Fig. 5, a pencil holder 60 of knownform being there illustrated with a lead 6| releasably held therein. Thesame type of cylindrical stem 4| is fixed to the pencil holder 66 as isfixed to the pen illustrated in Fig. 1, and the same type of transversepin 42 is fixed to the cylindrical stem 4| for the same purpose as thatheretofore described.

Fig. 6 illustrates how the curve scriber may be employed to scribe theovoid form there illustrated. For this purpose double conical locationelements 56 are inserted at points A, B and C, which are spaced toprovide the desired scribed form. The thread 52 is looped around thecentral waists 51 of these location elements, adjustment of the lengthof looped thread is made by turning the knurled head 5| and the standardI l is moved around the location elements in order to scribe the ovoidform.

In Fig. 'l a method of scribing a spiral curve is illustrated. In thiscase four double conical location elements 56 are positioned at pointsW, X, Y and Z closely together. The thread 52 is looped over but one ofthe location elements,

and the length of the looped thread is suitably adjusted. The spiral isthen scribed by giving wound from them. The result is a spiral curvesuch as that illustrated.

Obvious methods of scribing other curves may, 'of course, be employed.

From the foregoing it will be apparent that the present inventionprovides a simple, inexensive and rugged curve scriber which is easilyadjusted and used to scribe a variety of different curves. Because ofthe simplicity of its adjustment, that adjustment is retained withoutdifficulty. Furthermore, the curve scriber minimizes the effect of thehuman equation in using the instrument.

The form of the invention here described and illustrated is presentedmerely as an example of how the invention may be embodied and applied.Other forms, coming within the proper scope of the appended claims, willreadily suggest themselves to those skilled in the curve scribing art.

I claim:

1. A curve scriber comprising: a standard including a foot having aplane lower surface adapted to rest slidably upon the surface upon whicha curve is to be scribed, and a shaft fixed to said foot and extendingperpendicularly therefrom; a bracket hinged to said shaft, said bracketincluding two parallel plates; a marking element holder slidablyconnected to said bracket for motion at right angles to said shaft; amarking element slidable in said marking element holder in the directionin which said shaft extends to contact the surface upon which the curveis to be scribed with its scribing end; and a looped thread adjustablyconnected to said marking element holder for looped connection about aplurality of location elements to determine the changing position ofsaid marking element while scribing a curve.

2. A curve scriber comprising: a standard including a foot having aplane lower surface adapted to rest slidably upon the surface upon whicha curve is to be scribed, a shaft fixed to said foot and extendingperpendicularly therefrom, and a sleeve closely fitted upon said shaftfor rotation thereon; a bracket fixed to said sleeve, said bracketincluding two parallel plates; a, marking element holder slidablyconnected to said bracket for motion at right angles to said shaft; amarking element slidable vertically in said marking element holder tocontact the surface upon which the curve is to be scribed with itsscribing end; and a looped thread adjustably connected to said markingelement holder for looped connection about a plurality of locationelements to determine the changing position of said marking elementwhile scribing a curve.

3. A curve scriber comprising: a standard including a foot having aplane lower surface adapted to rest slidably upon the surface upon whicha curve is to be scribed, a shaft fixed to said foot and extendingperpendicularly therefrom, and a sleeve closely fitted upon said shaftfor rotation thereon; a bracket fixed to said sleeve, said bracketincluding two parallel plates; a, marking element holder slidablyconnected to said bracket for motion at right angles to said essence ashaft; said marking "elementholder including a vertical tubular member,a forked member fixed to said tubular member and spring-restrainedbetween said parallel'plates, and a thread reel; a marking elementslidable vertically in said tubular member to contact the surface uponwhich the curve is to be scribed with its scribing end; and a loopedthread adjustably connected to said thread reel for looped connectionabout a plurality of location elements to determine the changingposition of said marking element while scribing a curve.

4. A curve scriber comprising: a standard including a foot having aplane lower surface adapted to rest slidably upon the surface upon whicha curve is to be scribed; a bracket hinged to said standard to swingcompletely thereabout in fixed horizontal position; a marking elementholder slidably connected to said bracket for motion at right angles tosaid standard, said marking element holder including a vertical tubularmember, a thread reel, and a downwardly extending thread guiding memberhaving an opening and a terminal slot therein; a marking elementslidable vertically in the vertical tubular member of said markingelement holder to contact the surface upon which the curve is to bescribed with its scribing end; and a looped thread connected to saidthread reel and passing through the opening and the terminal slot insaid thread guiding member for looped connection about a plurality oflocation elements to determine the changing position of said markingelement while scribing a curve.

5. A curve scriber comprising: a standard including a foot having aplane lower surface adapted torest' slidably on the surface upon" whicha curve is to be scribed; a bracket hinged to said standard to swingcompletely thereabout in fixed horizontal position; a marking elementsholder slidably connected to said bracket for motion at right angles tosaid standard, said marking element holder including a, vertical tubularmember, a thread reel, and a downwardly extending thread guiding memberhaving an opening and a terminal slot therein; a marking elementslidable vertically in the vertical tubular member of said markingelement holder to contact the surface upon which the curve is to bescribed with its scribing end; a plurality of double conical locationelements in ended for fixation at suitable points on the surface uponwhich a curve is to be scribed; and a looped thread connected to saidthread reel and passing through the opening and the terminal slot insaid thread guiding member for looped connection about said plurality oflocation elements to determine the changing position of said markingelement while scribing a curve.

